Preheat your oven to 350°F (175°C).
Cream the butter and sugar together in a mixing bowl until light and fluffy.
Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
In another bowl, whisk together the gluten-free flour, cocoa powder, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients, alternating with the milk. Mix until just combined.
Line a cupcake pan with paper liners and fill each liner about two-thirds full with batter.
Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.
Let the cupcakes cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.